Cosmic-ray anisotropy in the north–south direction

For the study of a cosmic-ray anisotropy in the north–south direction, the day-to-day variation of the difference (N–S) of cosmic-ray neutron intensities between the arctic and the antarctic was examined with respect to solar rotations. Harmonic analysis on the variation of the intensity difference...

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Bibliographic Details
Published in:Canadian Journal of Physics
Main Authors: Murakami, K., Kudo, S.
Format: Article in Journal/Newspaper
Language:English
Published: Canadian Science Publishing 1968
Subjects:
Online Access:http://dx.doi.org/10.1139/p68-363
http://www.nrcresearchpress.com/doi/pdf/10.1139/p68-363
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Summary:For the study of a cosmic-ray anisotropy in the north–south direction, the day-to-day variation of the difference (N–S) of cosmic-ray neutron intensities between the arctic and the antarctic was examined with respect to solar rotations. Harmonic analysis on the variation of the intensity difference shows the existence of a recurrent variation with half the period of a solar rotation. Such a recurrent variation is closely connected with the rapid phase changes of the cosmic-ray diurnal variation during a solar rotation. Regarding the sectored structure of solar wind reported by Wilcox and Ness, the intensity difference (N–S) increases when the earth is passing near a boundary from the (+) sector into the (−) sector, while it decreases near the other boundary. This N–S anisotropy of cosmic rays seems to be caused by the transitional change of cosmic-ray trajectories near the sector boundary and by the spatial distribution of cosmic-ray flux.